Scalable Multi-Voltage-Level Optimal Power Flow for Curative Grid Curtailment Measures

In the course of the energy transition, an increase in controllable units in the distribution grids is to be expected, which can be used to delay or avoid grid expansion. The determination of an optimal power flow can be used to efficiently eliminate grid bottlenecks by curtailing these controllable units. The effort required to solve an optimal power flow (OPF) problem to curtail loads or generators increases greatly with the number of controllable grid participants and the complexity of the grid. In order to determine the optimal use of controllable grid participants in higher voltage levels, the flexibility of the lower voltage levels must also be taken into account. Therefore grids with several voltage levels must be considered. This complexity leads to high computing times. To solve this problem, we developed a method that makes it possible to curtail controllable participants in multi-voltage level grids in the event of limit violations considering (N-1)-safety by calculating the optimal power flow for different sub-grids separately. With the developed procedure, a runtime improvement of a factor of up to 358 can be achieved while receiving similar results as from a conventional OPF when applied on controllable loads in a medium and low voltage grid.